Is Onion Low FODMAP?

Very high FODMAP — the #1 IBS trigger. Onion is one of the highest-FODMAP foods and the single most common IBS trigger. It is high in fructans even in tiny amounts, and cooking does not remove them. Use the green tops of spring onions, or garlic/onion-infused oil, for flavour instead.
High FODMAPFructans
FODMAP levelHigh
Main FODMAP group(s)Fructans
Food category🥦 Vegetables

Low-FODMAP alternatives to Onion

If you are avoiding Onion, these are better tolerated on a low-FODMAP diet:

More vegetables and their FODMAP levels

Track Onion and your FODMAP triggers

JustAddTofu is a free iOS app that flags high-FODMAP foods as you log meals by voice — in 99+ languages, with no account required. It helps you run the low-FODMAP elimination and reintroduction phases and spot which foods set off your IBS.

Onion & FODMAP FAQ

Is Onion low FODMAP?

Very high FODMAP — the #1 IBS trigger. Onion is one of the highest-FODMAP foods and the single most common IBS trigger. It is high in fructans even in tiny amounts, and cooking does not remove them. Use the green tops of spring onions, or garlic/onion-infused oil, for flavour instead.

Can I eat Onion on a low-FODMAP diet?

Onion is high FODMAP and best avoided during the elimination phase, as it is high in Fructans. Reintroduce carefully later to find your personal tolerance.

What are low-FODMAP alternatives to Onion?

Low-FODMAP swaps include Carrots. These are better tolerated than Onion on a low-FODMAP diet.

Last reviewed June 2026. FODMAP ratings are based on Monash University low-FODMAP guidance and general dietary references. FODMAP tolerance and serving sizes are individual — this is general information, not medical advice. Track your own response and work with a dietitian on elimination and reintroduction.

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